Islanabilirlik Gradyan Yüzeylerinde Kendi Kendini Yürüten ve Birleştiren Damlacıklar: Bir Lattice Boltzmann Çalışması

Öz

Damlacıkların kendi kendine taşınması ve kontrolü, mikroakışkan cihazların geliştirilmesinde, kendi kendini temizlemede, su toplamada ve ısı transferini geliştirmede önemli bir rol oynar. Yüzeylerde bir ıslatma gradyanı yapılandırılmışsa, harici bir kuvvet olmadan damlacık manipülasyonu elde edilebilir. Temas açısı histerezisi, daha çok ıslanan tarafa doğru bir itici güç oluşturur. Bu kuvvet, hareketli temas hatlarının yakınındaki viskoz gerilimlerle dengelenirse, bu tür yüzeyler üzerindeki damlacıklar, bu denge tarafından belirlenen sabit öteleme hızına ulaşabilir. Bu çalışmada D2Q9 lattice Boltzmann yöntemi, ıslanabilirlik gradyan yüzeylerinde kendiliğinden hareket eden damlacıkların simülasyonu için kullanılmıştır. Yüzey enerjisi ve akışkan viskoziteleri değiştirilerek, tek damlacıkların yüzeyler üzerindeki davranışı, bunların birleştirme mekanizması ve sınırlandırılmış kanallar içindeki denge şekilleri ve hareketleri sistematik olarak incelenmiştir. Damlacık daha viskoz bir akışkan içinde hareket ederse, damlacık hızının ıslanma gradyanına bağlılığının zayıfladığı gözlemlenmiştir. Büyük görünüm oranlı kanal akışları için, arayüz hareketinin iki boyutlu tahmininin üç boyutlu D3Q19 modeli hesaplamalarına yaklaştığı gösterilmiştir.

Anahtar Kelimeler

• Arayüzey akışı
• Temas hattı
• Islanabilirlik gradyanı
• Lattice Boltzmann metodu

Self-Driving and Merging Droplets on Wettability Gradient Surfaces: A Lattice Boltzmann Study

Öz

Self-transport and control of droplets play an essential role in the development of microfluidic devices, self-cleaning, water harvesting, and heat transfer enhancement. Droplet manipulation without an external force can be accomplished if a wetting gradient is structured on surfaces. The contact angle hysteresis generates a driving force toward the more wetting side. If this force is balanced by the viscous stresses near moving contact lines, droplets on such surfaces may attain constant translational speed determined by this balance. The D2Q9 lattice Boltzmann method is employed for the simulation of the self-driven droplets on wettability gradient surfaces. By varying the surface energy and fluid viscosities, the behavior of single droplets on surfaces, their merging mechanism, and equilibrium shapes and motions within confined channels are studied systematically. If the droplet moves in a more viscous fluid, the droplet’s speed dependence on the wetting gradient is observed to weaken. For large aspect ratio channel flows, it is shown that two-dimensional prediction of the interface motion approaches the three-dimensional D3Q19 model computations.

Anahtar Kelimeler

• Interfacial flow
• Contact line
• Wettability gradient
• Lattice Boltzmann method

Kaynakça

1. [1] Wu, L., Guo, Z., Liu, W. 2022. Surface behaviors of droplet manipulation in microfluidics devices, Advances in Colloid and Interface Science, vol. 308(102770).
2. [2] Gosh, A., Ganguly, R., Schutzius, T. M., Megaridis, C. M. 2014. Wettability patterning for high-rate, pumpless fluid transport on open, non-planar microfluidic platforms, Lab. Chip, 14, 1538-1550.
3. [3] Oliveira, N. M., Vilabril, S., Oliveira, M. B., Reis, R. L., Mano, J. F. 2018. Recent advances on open fluidic systems for biomedical applications: A review, Mater. Sci. Eng. C. Mater. Biol. Appl., 97, 851-863.
4. [4] Singh, M., Kondaraju, S., Bahga, S. S. 2018. Mathematical Model for Dropwise Condensation on a Surface with Wettability Gradient, Journal of Heat Transfer, 140(071502).
5. [5] Hassan, G., Yilbas, B.S., Al-Sharafi, A., Al-Qahtani, H. 2019. Self-cleaning of a hydrophobic surface by a rolling water droplet, Sci. Rep., 9(5744).
6. [6] Tenjimbayashi, M., K. Manabe, K. 2022. A review on control of droplet motion based on wettability modulation: principles, design strategies, recent progress, and applications, Science and Technology of Advanced Materials, 23(1), 473- 497.
7. [7] Shen, C., Liu, L., Wu, S., Yao, F., Zhang, C. 2020. Lattice Boltzmann simulation of droplet condensation on a surface with wettability gradient, Journal of Mechanical Engineering Science, vol. 234(7),1403-1413.
8. [8] Daniel, S., Chaudhury, M. K., Chen, J. C. 2001. Fast Drop Movements Resulting from the Phase Change on a Gradient Surface, Science, 291, 633- 636.

9. [9] Mistura, G., Pierno, M. 2017. Drop mobility on chemically heterogeneous and lubricantimpregnated surfaces, Adv. in Phys.: X, 2, 591-60.
10. [10] Sadullah, M. S., Kusumaatmaja, H., Launay, G., Parle, J., Ledesma-Aguilar, R., Gizaw, Y., McHale, G., Wells, G. G. 2020. Bidirectional motion of droplets on gradient liquid infused surfaces, Comm. Phys., 3(166).
11. [11] Chen, L., Gao, M., Liang, J., Wang, D., Hao, L., Zhang, L. 2022. Lattice Boltzmann simulation of wetting gradient accelerating droplets merging and shedding on a circumferential surface, Eng. App. of Comp. Fluid Mech., 16.
12. [12] Qu, J., Yang, X., Wang, Z. 2020. Numerical simulations on the self-motion of droplets in hydrophobic microchannels driven by wettability gradient surfaces, Int. Comm. in Heat and Mass Trans., 119(104961).
13. [13] Li, C., Dai, H., Gao, C., Wang, T., Dong, Z., Jiang, L. 2019. Bioinspired inner microstructured tube controlled capillary rise, PNAS, vol. 116(26), 12704-12709.
14. [14] Moumen, N., Subramanian, R. S., McLaughlin, J. B. 2006. Experiments on the Motion of Drops on a Horizontal Solid Surface Due to a Wettability Gradient, Langmuir, 22(6), 2682-2690.
15. [15] Raphael, E. 1988. Spreading of droplets on a patchy surface, C. R. Acad. Sci. Paris, 306, 751- 754.
16. [16] Xu, X., Qian, T. 2012. Droplet motion in onecomponent fluids on solid substrates with wettability gradients, Phys. Rev. E., 85(051601).
17. [17] Thomas, T. M., Chowdhury, I. U., Dhivyaraja, K., P. Mahapatra, S., Pattamatta, A., Tiwari, M. K. 2021. Droplet Dynamics on a Wettability Patterned Surface during Spray Impact, Processes, 9(555).
18. [18] Wang, X., Xu, B., Chen, Z. 2020. Numerical simulation of droplet dynamics on chemically heterogeneous surfaces by lattice Boltzmann method, Int. Jour. of Num. Meth. for Heat & Fluid Flow, 30(2), 607-624.
19. [19] Chowdhury, I. U., Mahapatra, P. S., Sen, A. K. 2019. Self-driven droplet transport: Effect of wettability gradient and confinement, Physics of Fluids, 31(042111).
20. [20] Chowdhury, I. U., Mahapatra, P. S., Sen, A. K. 2020. Shape evolution of drops on surfaces of different wettability gradients, Chemical Engineering Science, 229(116136).
21. [21] Gulfam, R., Chen, Y. 2022. Recent Growth of Wettability Gradient Surfaces: A Review, A Review Research, 2022(9873075).
22. [22] Ding, Y., Yin, L., Dang, C., Liu, X., Xu, J. 2023. Selfclimbing of a low surface tension droplet on a vertical conical surface, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 658( 130670).
23. [23] Raj, S. S., Mathew, R. M., Davis, D., Varanakkottu, S. N., Srinivasan, A., & Vinod, T. P. 2023. Facile fabrication of stable wettability gradients on elastomeric surfaces for applications in water collection and controlled cell adhesion. Soft Matter, 19(29), 5560-5574.
24. [24] Xie, D., Sun, Y., Wu, Y., Wang, K., Wang, G., Zang, F., & Ding, G. 2023. Engineered Switchable‐ Wettability Surfaces for Multi‐Path Directional Transportation of Droplets and Subaqueous Bubbles. Advanced Materials, 35(9), 2208645.
25. [25] Sung, J., Lee, H. M., Yoon, G. H., Bae, S., & So, H. 2023. One-step fabrication of superhydrophobic surfaces with wettability gradient using threedimensional printing. International Journal of Precision Engineering and Manufacturing-Green Technology, 10(1), 85-96.
26. [26] Pooley, C. M., Kusumaatmaja, H., Yeomans, J. M. 2008. Contact line dynamics in binary lattice Boltzmann simulations, Phys. Rev. E., 78(056709).
27. [27] Briant A. J., Yeomans J. M. 2004. Lattice boltzmann simulations of contact line motion. ii. binary fluids, Physical Review E, 69(031603).
28. [28] Frisch, U., d'Humières, D., Hasslacher, B., Lallemand, P., Pomeau, Y. and Rivet, J.P. 1987. Lattice gas hydrodynamics in two and three dimensions, Complex Systems, 1 (649-707).
29. [29] Pooley, C.M., Furtado, K. 2008. Eliminating spurious velocities in the free-energy lattice Boltzmann method, Physical Review E, 77(046702).
30. [30] Pooley, C. M., Kusumaatmaja, H., Yeomans, J. M. 2009. Modelling capillary filling dynamics using lattice Boltzmann simulations, Eur. Phys. J. Special Topics, 171, 63-71.
31. [31] Boylu, M. A. 2023. Controlling the Motion of Capillary Driven Interfaces in Channels with Chemical Heterogeneity. İzmir Katip Çelebi University, Graduate School of Natural and Applied Sciences, Master’s Thesis, 68 pg., İzmir.
32. [32] Broachard, F. 1989. Motions of Droplets on Solid Surfaces Induced by Chemical or Thermal Gradients, Langmuir, 5, 432-438.
33. [33] Ceyhan, U., Tiktaş, A., Özdoğan, M. 2020. Pinning and depinning of Wenzel-state droplets around inclined steps, Colloid and Interface Science Communications, 35(100238).